Showing papers by "K. van Bibber published in 2010"

Review of Particle Physics

Abstract: This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2158 new measurements from 551 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 108 reviews are many that are new or heavily revised including those on neutrino mass, mixing, and oscillations, QCD, top quark, CKM quark-mixing matrix, V-ud & V-us, V-cb & V-ub, fragmentation functions, particle detectors for accelerator and non-accelerator physics, magnetic monopoles, cosmological parameters, and big bang cosmology.

SQUID-based microwave cavity search for dark-matter axions.

Abstract: Axions in the $\ensuremath{\mu}\mathrm{eV}$ mass range are a plausible cold dark-matter candidate and may be detected by their conversion into microwave photons in a resonant cavity immersed in a static magnetic field. We report the first result from such an axion search using a superconducting first-stage amplifier (SQUID) replacing a conventional GaAs field-effect transistor amplifier. This experiment excludes KSVZ dark-matter axions with masses between $3.3\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ and $3.53\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ and sets the stage for a definitive axion search utilizing near quantum-limited SQUID amplifiers.

Search for Hidden Sector Photons with the ADMX Detector

Abstract: Hidden U(1) gauge symmetries are common to many extensions of the standard model proposed to explain dark matter. The hidden gauge vector bosons of such extensions may mix kinetically with standard model photons, providing a means for electromagnetic power to pass through conducting barriers. The axion dark matter experiment detector was used to search for hidden vector bosons originating in an emitter cavity driven with microwave power. We exclude hidden vector bosons with kinetic couplings $\ensuremath{\chi}g3.48\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ for masses less than $3\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$. This limit represents an improvement of more than 2 orders of magnitude in sensitivity relative to previous cavity experiments.

Search for chameleon scalar fields with the axion dark matter experiment.

Abstract: Scalar fields with a 'chameleon' property, in which the effective particle mass is a function of its local environment, are common to many theories beyond the standard model and could be responsible for dark energy. If these fields couple weakly to the photon, they could be detectable through the afterglow effect of photon-chameleon-photon transitions. The ADMX experiment was used in the first chameleon search with a microwave cavity to set a new limit on scalar chameleon-photon coupling {beta}{sub {gamma}}excluding values between 2x10{sup 9} and 5x10{sup 14} for effective chameleon masses between 1.9510 and 1.9525 {mu}eV.

A Search for Scalar Chameleons with ADMX

Abstract: Scalar fields with a “chameleon” property, in which the effective particle mass is a function of its local environment, are common to many theories beyond the standard model and could be responsible for dark energy. If these fields couple weakly to the photon, they could be detectable through the “afterglow” effect of photon-chameleon-photon transitions. The ADMX experiment was used in the first chameleon search with a microwave cavity to set a new limit on scalar chameleon

Probing the eV-Mass range for solar axions with CAST

Abstract: The CERN Axion Solar Telescope (CAST) is searching for solar axions which could be produced in the core of the Sun via the so-called Primakoff effect Not only would these hypothetical particles solve the strong CP problem, but they are also one of the favored candidates for dark matter In order to look for axions originating from the Sun, CAST uses a decommissioned LHC prototype magnet In its 10 m long magnetic field region of 9 Tesla, axions could be reconverted into X-ray photons Different X-ray detectors are installed on both ends of the magnet, which is mounted on a structure built to follow the Sun during sunrise and sunset for a total of about 3 hours per day The analysis of the data acquired during the first phase of the experiment with vacuum in the magnetic field region yielded the most restrictive experimental upper limit on the axion-to-photon coupling constant for axion masses up to about 002 eV In order to extend the sensitivity of the experiment to a wider mass range, the CAST experiment continues its search for axions with helium in the magnet bores In this way it is possible to restore coherence of conversion for larger masses Changing the pressure of the helium gas enables the experiment to scan different axion masses in the range of up to about 12 eV Especially at high pressures, a precise knowledge of the gas density distribution is crucial to obtain accurate results In the first part of this second phase of CAST, 4He was used and the axion mass region was extended up to 039 eV, a part of phase space favored by axion models In CAST's ongoing 3He phase the studied mass range is now being extended further In this contribution the final results of CAST's 4He phase will be presented and the current status of the 3He run will be given This includes latest results as well as prospects of future axion experiments